Pat Bodger, an electrical engineer at the University of Canterbury and
one of the inventors of a transduction water heater, responded.

The word induction in this sense refers to inducing an electric current in
metal using a changing magnetic field, rather than having a contact method
like the resistive elements in a hob.

With induction heating, heat is produced directly in the pot
rather than being conducted from a hot element. This way, only the pot, and
hence the water and food, is heated. The element stays relatively cool.

The idea works on pots made of steel, copper or aluminium. Just how well
depends on their shape and size. You would need to experiment with this.
The magnetic field is generated by designing a copper coil in the space of
the hob where a normal resistance element is placed. The coil is put in a
horizontal position so that the magnetic field goes up through the pot and
then out the sides and around the coil and back up again.

We use alternating current, as the currents induced in the pots only occur if the
magnetic field is changing. We can use mains frequency, 50Hz, or a higher
frequency, but that needs a changer which adds to the cost and complexity.